How to make a 14-Day Trial limit in my Delphi application

Question

Hi,

I'm looking to add a 14-Day trial limit to my software. The program has been written in Delphi 7.

Any help would be much appreciated.

Answer 1

You could try Turbopower OnGuard. This is now opensource.

http://sourceforge.net/projects/tponguard/

Answer 2

There are several tricks you can use, but none of them 100% fail save.

• You can use some kind of licensing mechanism.
• You can store the setup time somewhere hidden in the registry.
• You can store the setup time in a file (possibly an executable file or dll).
• You can store the IP address in a central database and check each time if the 14 days are passed (you need a internet connection for that).
• You can create a file (for example a dll) dynamically on your server and have the installer retreive that file. (Be sure to log the IP so a second attempt will not be possible).

But I think the best way, is to give trial versions with limited functionality. For example: No printing, no save of project, or only small projects can be saved.

That way you avoid the hassle and possible clients can take the time to evaluate your project.

EDIT: If you build a mechanism to check against roling back the clock. Be sure to build in a margin, else the program will be locked if you travel back to an other timezone. Or put the clock back in wintertime. I think a margin of 25 hour will cover everything. (And to be at the save side, you can build in a limit else, the user can roll back the time each day.).

But the best way to keep paying customers, is giving good support. I discontinue products if the service is bad.

Answer 3

One of the things you need to guard against with a time-limited application is users' rolling their calendar back so the application still works. One way around this is to store in your hidden registry place (or wherever) a timestamp whenever the application is started up. If the current date/time is ever earlier than the last timestamp recorded by your app, that means the user has rolled the calendar back and you should disable the application.

Time-limitation is a real pain, though, both for the programmer and the user. It's also not a great marketing idea: why go to the trouble of distributing promotional material (which is what your trial version is) that has an expiration date? It would be like a company mailing out advertisements on paper designed to disintegrate after two weeks.

If your trial version is functionally crippled instead, you might still get sales out of it even months or years later.

Answer 4

You can find the similar question here.

On general note i find time restriction much more useful than functionality restriction. As i explained in the comment to Gamecat post

Answer 5

I would recommend making a trial serial number with timestamp and force user to enter it into software when its installed. You can even automate it by calling server side page after setup is done.

Timestamp in trial serial key allows you to extend their trial if needed.

In addition you can count backwards to avoid user from changing year when installing:

e.g. if you have 14 days trial generated at 15.11.2008 (server time), you can check that locate date must be greater than 1.11.2008 or less than 24.11.2008 always when serial is used or entered.

Answer 6

something to be aware of when performing any of these checks. That the date is never GREATER than 14 days from the date you entered in either direction. A common method around most of these types of limits is to set the date a few years in advance, install and run your software, then set the date back to the current time. If you are hard coded to die 14 days from the original start date, then the user has a few years to try your software. Checking the other direction also gives the user at most 28 days.

Answer 7

You might want to read this page. It's a bit old, but smart info about protecting your program how and why.

Answer 8

I have used Armadillo, Asprotect and Winlicense. Both Armadillo and Asprotect have had serious problems, such as being considered viruses/trojans by some AVs, incompatibility problems, etc.

I haven't used Winlicense enough to have much of an opinion, but support is pretty great.

Obviously both are more complete solutions than what you are asking for - they include protection, licensing, keys, etc.

As mentioned by others, sometimes limiting a feature or adding a watermark is the best option. I've added a watermark to one of my programs (STGThumb) and sales went up about 400%...